Patent EP-0233099-B1 (EP)
IPC: F04B11/00
Filed: 1987-01-13
Granted: 1989-03-15
Abstract: 1. A process for controlling the delivery rate of paint with a view to regulating the thickness of the layer of paint applied to the ground by a device for pressurizing said paint in order to spray the paint through at least one nozzle, in particular for forming marking strips, said device, in addition to at least one nozzle (3) through which the paint (4) is sprayed, comprising : - a paint circuit (13) connected to the inlet of each nozzle (3), - a paint reservoir (5) in which the inlet (131) of the paint circuit (13) is submerged, - a paint pump (6) arranged in th paint circuit (13) between the reservoir (5) and the nozzle (3), which pump divides the circuit into a high pressure section (132) connected to the nozzle and a low pressure section (133) connected to the reservoir ; - a hydraulic motor (7) for driving the paint pump (6), - a hydraulic circuit (12) connected to the inlet (121) and outlet (122) of the hydraulic motor (7), - at least one reservoir (9) of hydraulic fluid (8) in which the inlet (123) and outlet (124) of the hydraulic circuit (12) are submerged, - a hydraulic pump (10) arranged in the hydraulic circuit (12) between the reservoir (9) and the inlet (121) of the hydraulic motor (7), - a drive menas (11) such as a motor or a power take-off controlling the hydraulic pump (10), and - means (14) for controlling the delivery rate, said control process being characterised in that : during installation : - in place of a rotary pump for driving the pain (4) to the nozzle (3), a reciprocating valve pump (6) is arranged in the paint circuit, the piston (61) of said pump comprising a dynamic joint (62) and dividing the cylinder (63) into two chambers (64, 65), the first (64) connected to the nozzle (3), the other (65) to the reservoir (5), the chamber (64) connected to the nozzle (3) housing the rod of the piston (61), the cross section of which rod is such that this chamber has a usable cross section which is equal to half that of the other chamber (65), - in place of a rotary hydraulic motor in order to control said pump (6), a reciprocating motor (7) is arranged in the hydraulic circuit, the piston (71) of said motor comprising a dynamic joint (72) and defining two chambers (74, 75), one of which (74) houses the rod (76) of the piston (71), the cross section of which rod is such that this chamber (74) has a usable cross section which is equal to half that of the other chamber (75), the chambers (74, 75) of the motor (7) being connected in parallel to the circuit (12) leading from the hydraulic pump (10) which ensures, at least for the chamber (75) having the largest usable cross section and by means of a remote control distribution member (77), that the effects of the hydraulic forces on the piston are equal in both directions of movement, - in order to equalize the delivery rate in spite of variations due to a pump of this type, a damping device (67) is connected to the high pressure section (132) of the paint circuit (13) at the outlet of the pump (6). . during initialisation, using suitable means (16), the proportional relationship (21) is determined between, on the one hand, the hydraulic delivery rate (23) supplying the hydraulic motor (7) and, on the other hand, the delivery rate (22) of the paint provided by the paint pump (6) controlled by said hydraulic motor (7), then . during use, in order to monitor the delivery rate in the paint circuit (13), a flow meter (15) is arranged not in said paint circuit but in the hydraulic circuit (12) and preferably between the hydraulic pump (10) and the hydraulic motor (7) and then . the signal (209 emitted by the flow meter (15) is read and said signal (20) is converted by suitable means (17), as a function of said proportional relationship (21), in order to obtain a signal (24) which is representative of the actual delivery rate of the paint.